<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="btn">获取数据</button>

    <script>
        let btn = document.getElementById('btn');
        btn.addEventListener('click',() => {
            fetch('http://localhost:3000')
            .then(res => res.json())
            .then(data => {
                console.log(data);
            })
        });
    </script>
</body>
</html>